Conventionally, using a reaction gas chromatograph of this kind, measurement of concentrations of various kinds of organic compounds contained in, for example, exhaust gas of an internal combustion engine and photochemical smog has been performed. More specifically, as shown in following equations, organic compounds contained in a sample gas are reacted with an oxidizing gas (oxygen) in an oxidation reaction part having an oxidation catalyst and decomposed into CO2 and water. Further, in a reduction reaction part having a reduction catalyst, the CO2 is reduced with reducing gas (hydrogen) to be converted to methane. For example, each of the reactions is as follows:CxHyOx+(x+y/4−z/2)O2→xCO2+(2/y−z)H2O  Oxidation reaction partxCO2+4xH2→xCH4+2xH2O  Reduction reaction part
Then the concentration of the methane generated by the reaction is measured by, for example, FID, and the concentration of the methane is divided by the number of carbon atoms x contained in one molecule of the organic compounds to thereby measure the concentration of the organic compound contained in the sample gas.
Meanwhile, if the sample gas contains, for example, halogen such as chlorine and sulfur, these components are reacted in the reduction reaction part to thereby generate hydrogen halide, sulfuric acid and the like, and this results in causing corrosion of a metal pipeline, deterioration of a reduction catalyst and reduction in sensitivity of the FID.
In order to prevent occurrence of such problems, in the gas chromatograph disclosed in Patent Literature 1, an adsorbent made of a porous material of such as activated carbon is provided in an intermediate gas flow path which connects between the oxidation reaction part and the reduction reaction part, and it is configured so that the measurement non-related components such as halogen and sulfur do not pass through and the measurement non-related components are prevented from reaching the reduction reaction part.
However, the adsorbent such as activated carbon adsorbs not only the measurement non-related components such as halogen and sulfur but also intermediate components CO2 and CO produced by the oxidation reaction part. Therefore, all the components CO2 and CO derived from the measurement target components contained in the sample gas will no reach the reduction reaction part and there occurs a quantitative error in such as a concentration of the measurement target components to be calculated. Similarly, there occurs a quantitative error in the gas chromatograph configured to measure the concentration of CO2 by NDIR without a reduction reaction part.